A laparoscopic instrument assembly with a handle member and a removable tip. The handle member and removable tip are mated using a double threaded design which provides a secure connection with low electrical resistance. Electrical energy is provided through an inner shaft to the removable tip, and a return energy path is formed using an outer tubing of the instrument assembly. The removal tip includes a cutting and sealing device with a resistive member that is provided with the electrical energy, thereby enabling the tip to cut and seal tissue.